An electric vehicle has the following problem. When the vehicle is traveling, the vehicle stops by running out of a battery, or the battery is damaged by overcharge. To address the above problem, Patent Document 1 discloses the following technique. An energy state of a battery mounted to a vehicle is determined. When the electricity is insufficient, the vehicle receives electricity supply from an outside of the vehicle. When the electric power is sufficient, the vehicle supplies the electricity to an outside of the vehicle.
Patent Document 1: JP-2005-210843
In the technique of Patent Document 1, the state of the battery is uniformly managed based on only the energy state of the battery at the present time. This technique involves the following problem. For example, let us assume that a vehicle is about to go downhill from now on. In this case, this vehicle stores electricity in the battery by regenerative braking or the like when going downhill. Thus, the manner of uniformly managing the energy state of the battery may cause overcharge when the vehicle is going downhill, and may have an adverse effect on the battery. In particular, if weight of load actually carried by the vehicle is larger than that according to a travel schedule, an amount of energy stored when the vehicle is going downhill increases, and the overcharge may easily occur.
It is assumed that the vehicle is about to travel on a hilly road from now on. In this case, an electricity consumption amount will become larger than when the vehicle will travel on a flat road. Thus, the manner of uniformly managing the enegery state of the battery may cause the run out of the battery while the vehicle is traveling. In particular, if weight of an object actually carried by vehicle is larger than that according to a travel schedule, an amount of energy consumed when the vehicle is traveling on the hilly road increases, and thus, the run out of the vehicle may easily occur.